旋转式过滤体颗粒捕集器流场分析

Research on Flow Field Analysis of Rotary Diesel Particulate Filter

以颗粒捕集器旋转式过滤体为研究对象,建立了旋转式载体的多孔介质仿真模型,在此模型基础上研究了旋转式过滤体内部气-粒两相流的速度场及其影响因素,分析了排气流速、直径比、进气扩张角等参数对过滤体内流动均匀性和涡流损失的影响规律,并据此提出了优化准则。研究结果表明:当颗粒捕集器入口流速从20 m/s提高至80 m/s时,过滤体内气流流动均匀性会增加,但流场基本结构变化微小;当过滤体直径比在4~6之间变化时,其数值越大,过滤体表面的流动均匀性越差,过滤体利用率越低,当直径比继续增加到超过某一特定数值后,过滤体内流场分布基本不再发生变化;当进气扩张角在60°~120°之间变化时,扩张角越大,颗粒捕集器扩张管内越容易产生涡流,并首先在过滤体相对位置为0.8的地方产生,随着扩张角的增大,涡流强度和区域都会增大,减小扩张角可以减弱过滤体内进气回流现象,改善流场分布均匀性。

The simulation model of porous media for rotary filter of diesel particulate filter was built and the velocity field and its influencing factors of gas-particulate two-phase flow inside filter were analyzed. The influences of exhaust velocity,diameter ratio and divergence angle on internal flow uniformity and turbulent flow loss were analyzed and the optimized criterion was put forward. The research results indicate that the uniformity of internal flow field improves and its structure still keeps unchanged when the inlet velocity of filter increases from 20 m/s to 90 m/s. When the diameter ratio increases from 4 to 6,the surface flow uniformity of filter gets worse and its utilization rate becomes lower. The distribution of internal flow keeps the same when the diameter ratio is beyond a certain value.When the divergence angle increases from 60 degree to 120 degree,the vortex is easier to produce inside the divergent tube and first happens in the relative axial position of 0.8. The vortex intensity and range increase with the increase of divergence angle. In order to reduce backflow and enhance uniformity of flow field,the divergence angle should decrease.